Node wise permissions greyed out

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Hi... Greetings. I'm trying to create some courses some of which are going to be free to all including anonymous users. I've created free course with public group visibility. But the contents of course are not visible to anybody except user 1. Playing with the settings I figured out that visibility of the fields e.g. body field and various options like Take Course etc need to be enabled in OG access settings at /admin/config/group/permissions/course. As far as I can understand these permissions are applicable to all the courses. What I want to do is that the permissions for free courses need to be more liberal than those for paid ones. I think that solution to my problem is per node permissions which are at /group/node/%/admin/permissions. My problem is that all the checkboxes are greyed out as you can see here. So What is wrong with my settings?